Possible signs: Fizzing, Bubbling, Exploding, Formation of Ice Crystals, Gas Being Released, New Substances Forming.
Reactant: A substance or molecule that participates in a chemical reaction. In the video above, the reactants are baking soda and vinegar.
Product: A substance that forms in a chemical reaction. In the video above, the product is the brownish-tan, bubbly foam that results from the two substances being put together in the same cup.